Bob Barnes for WaPo:

Stevens, who was joined by Chief Justice John G. Roberts Jr. and Justice Anthony M. Kennedy, mentioned a dozen times in the opinion that it was based on “the record” in the case.

“I learned a lot of things outside the record that made me very concerned about that statute,” Stevens said in the conversation with Kagan and Wood. “So I had the question: Should I rely on my own research or what’s in the record?”

“And I thought in that case I had a duty to confine myself to what the record did prove, and I thought it did not prove the plaintiffs’ case. And as a result, we ended up with a fairly unfortunate decision.”

Stevens alluded to his quandary in a footnote in the opinion: “Supposition based on extensive Internet research is not an adequate substitute for admissible evidence subject to cross-examination in constitutional adjudication.”

In the conversation, Stevens noted that dissenting justice David H. Souter did not share his reluctance.

“I thought David wrote one of his best opinions, relying partly on material that was outside the record,” Stevens said.